Some scope and interpolation fixes

src/ft2_main.c

@@ -23,6 +23,7 @@
 #include "ft2_sample_ed.h"
 #include "ft2_diskop.h"
 #include "scopes/ft2_scopes.h"
+#include "scopes/ft2_scopedraw.h"
 #include "ft2_about.h"
 #include "ft2_pattern_ed.h"
 #include "ft2_module_loader.h"
@@ -367,6 +368,7 @@ static void cleanUpAndExit(void) // never call this inside the main loop!
 	freeTextBoxes();
 	freeMouseCursors();
 	freeBMPs();
+	freeScopeIntrpLUT();
 
 	if (editor.audioDevConfigFileLocationU != NULL)
 	{

src/mixer/ft2_cubic_spline.c

@@ -5,7 +5,7 @@
 #include <stdint.h>
 #include <stdbool.h>
 #include <stdlib.h>
-#include "ft2_cubic_spline.h"
+#include "ft2_cubic_spline.h" // CUBIC_SPLINE_TAPS, CUBIC_SPLINE_PHASES
 #include "../ft2_video.h" // showErrorMsgBox()
 
 float *fCubicSplineLUT = NULL; // globalized

src/mixer/ft2_gaussian.c

@@ -1,6 +1,9 @@
 /*
-** Super Nintendo SPC700 interpolation LUT generator.
-** This has long believed to have a Gaussian curve, but it doesn't.
+** Super Nintendo (SPC700) Gaussian interpolation LUT generator
+**
+** It was long believed that it uses a Gaussian curve, but it doesn't!
+** We still call it Gaussian interpolation in the FT2 clone though, so
+** that people recognize it.
 **
 ** Based on code by Mednafen and nocash:
 ** https://forums.nesdev.org/viewtopic.php?t=10586
@@ -10,10 +13,17 @@
 #include <stdint.h>
 #include <stdbool.h>
 #include <stdlib.h>
-#include "ft2_gaussian.h"
+#include "ft2_gaussian.h" // GAUSSIAN_TAPS, GAUSSIAN_PHASES
+#include "../ft2_header.h" // PI
 #include "../ft2_video.h" // showErrorMsgBox()
 
-#define MY_PI 3.14159265358979323846264338327950288
+/*
+**  1.28 = Super Nintendo
+** 2.048 = Sony PlayStation (less aliasing on very low pitches)
+*/
+#define PI_MULTIPLIER 1.28
+
+#define TAP_SUM_SCALE 1.0
 
 float *fGaussianLUT = NULL; // globalized
 
@@ -40,18 +50,18 @@ bool calcGaussianTable(void)
 		const double x4 = (0.5 + i4) * (1.0 / ((GAUSSIAN_PHASES*4)-1));
 
 		// Blackman window
-		const double w1 = (0.42 + (0.50 * cos(2.0 * MY_PI * x1)) + (0.08 * cos(4.0 * MY_PI * x1))) / x1;
-		const double w2 = (0.42 + (0.50 * cos(2.0 * MY_PI * x2)) + (0.08 * cos(4.0 * MY_PI * x2))) / x2;
-		const double w3 = (0.42 + (0.50 * cos(2.0 * MY_PI * x3)) + (0.08 * cos(4.0 * MY_PI * x3))) / x3;
-		const double w4 = (0.42 + (0.50 * cos(2.0 * MY_PI * x4)) + (0.08 * cos(4.0 * MY_PI * x4))) / x4;
+		const double w1 = (0.42 + (0.50 * cos(2.0 * PI * x1)) + (0.08 * cos(4.0 * PI * x1))) / x1;
+		const double w2 = (0.42 + (0.50 * cos(2.0 * PI * x2)) + (0.08 * cos(4.0 * PI * x2))) / x2;
+		const double w3 = (0.42 + (0.50 * cos(2.0 * PI * x3)) + (0.08 * cos(4.0 * PI * x3))) / x3;
+		const double w4 = (0.42 + (0.50 * cos(2.0 * PI * x4)) + (0.08 * cos(4.0 * PI * x4))) / x4;
 
-		const double t1 = sin(1.28 * MY_PI * x1) * w1;
-		const double t2 = sin(1.28 * MY_PI * x2) * w2;
-		const double t3 = sin(1.28 * MY_PI * x3) * w3;
-		const double t4 = sin(1.28 * MY_PI * x4) * w4;
+		const double t1 = sin(PI_MULTIPLIER * PI * x1) * w1;
+		const double t2 = sin(PI_MULTIPLIER * PI * x2) * w2;
+		const double t3 = sin(PI_MULTIPLIER * PI * x3) * w3;
+		const double t4 = sin(PI_MULTIPLIER * PI * x4) * w4;
 
-		// normalization value (assures unity gain when summing taps)
-		const double dScale = 1.0 / (t1 + t2 + t3 + t4);
+		// calculate normalization value (also assures unity gain when summing taps)
+		const double dScale = TAP_SUM_SCALE / (t1 + t2 + t3 + t4);
 
 		*fPtr++ = (float)(t1 * dScale);
 		*fPtr++ = (float)(t2 * dScale);

src/mixer/ft2_gaussian.h

@@ -6,7 +6,7 @@
 
 #define GAUSSIAN_TAPS 4
 #define GAUSSIAN_WIDTH_BITS 2 // log2(GAUSSIAN_TAPS)
-#define GAUSSIAN_PHASES 8192
+#define GAUSSIAN_PHASES 8192 /* originally 256 on SNES/PSX, but more is better! */
 #define GAUSSIAN_PHASES_BITS 13 // log2(GAUSSIAN_PHASES)
 #define GAUSSIAN_FSHIFT (MIXER_FRAC_BITS-(GAUSSIAN_PHASES_BITS+GAUSSIAN_WIDTH_BITS))
 #define GAUSSIAN_FMASK ((GAUSSIAN_TAPS*GAUSSIAN_PHASES)-GAUSSIAN_TAPS)